Process and means for the stepwise variation of the output of multicylinder plunger pumps



fifllfi fll 76 G. SILVESTRI PROCESS AND MEANS FOR THE STEPWISE VARIATION OF THE OUTPUT OF Sept. 18 1923.

MULTICYLINDER PLUNGER PUMPS Filed Sept. 22. 3 Sheets-Sheet 1 I N VEN TR 3% by W 7% A WORN 5/5- sepk. 18 I923.

PROCESS AND MEANS FOR THE MULTI ESTRI STEPW VARIATION O CYLINDER PLUNGER PUM led Sent. 22 1922 HE OUTPUT OF 3 Sheets-Sheet 2 INVENTOH Sept. 18 1923. 9 6

s1 ESTRI PROCESS AND MEANS FOR THE PW VARIATION OF THE OUTPUT 0F MULTIGYLINDER PLUNGER PUMPS Filed Sept. 22. 1922 s Sheets-Sheet 5 INVENTOH section,

Patented ept. 18, 1923.

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Persia osic.

GIULIO SILVESTRI, OF TRIEST, ITALY.

PROCESS AND MEANS FOR THE STEPWISE VARIATION OF THE OUTPUT OF MULTIF CYLINDER PLUNGER PUMPS.

Application filed September 22, 1922. Serial No. 589,926.

To all whom it may concern:

Be it known that I, GiULIo SILVESTRI, a subject of the Kin of Italy, residing at 1064 S. Giovanni, riest, in the county of Julian Venetia and Kingdom of Italy, have invented certain new and useful Improvements in a Process and Means for the Stepwise Variation of the Output of Multicylinder Plunger Pumps, of which the following is a specification. I

This invention relates to a process and means for the stepwise variation of the output of multi-cylinder plunger pumps and particularly relates topumps in which the cylinders and suction valves are arranged in radial groups.

According to the presentinvention by a stepwise rotation of means combined with the suction valves an increasing number of pumps may be placed out of action during the successive regulating positions by holding their suction valves continuously open.

When passing from one regulating position to another entire groups of pumps, which even may belong to different groups of cyl inders may also be placed out of action.

The accompanying drawings illustrate,by way of example, one mode of carrying out the present invention. In the drawin Fig. 1 shows t e pump in longitudinal Fig. 2 is a cross-sectional view of the pump, the section being taken on line 0-0! of Fig. 1

Fig. 3 illustrates a cam-disc, and

Fig. 4 a diagrammatic view of the pump aggregate with the cam disc.

The pump illustrated in Figs. 1 and 2 comprises twelve cylinders arranged in two groups, each group comprising six radially disposed cylinders. One group'is arranged in the plane o v and the other group in the plane r'r (Fig. 1). The cylinders of the same group are disposed at degrees with respect to each other, whilst the two groups are displaced at 30 degrees to one another. The six pistons of each group or rather their piston rods are connected to a common two throw crank shaft, the two cranked portions thereof (one to each group) being displaced at 180 degrees with respect to each other.

As will be seen from Fig. 4, the six cylinders arranged in the plane o-o are designated with It), 1141,1110), IV'v, vii, V11; and

the six cylinders 1 ing in the plane 1' r with Ir, Hr, H11, 1 1", V7, V11". As already stated the piston rods ;0 of each group act on a common crank shaft, the crank-portions for the groups being designated by Z2; and Z1 respectively. The pumps are single-acting and the side of the cylinder of each pump facing the crank shaft is open and does no work. The other cylinder-side of eve pump communicates with a special suction chamber Si) or Sr respectively. The suction chambers are separated from vone another, e. g. they are not in communication with each other, and their number corresponds to the number of cylinders employed. The suction chambers So of the first group are shorter than the suction chambers Sr of the second group, and as may be seen from Fig. 1 the longer suction chambers Sr pass between the cylinders of the first group. Everyone of the twelve suction chambers is provided with a suction valve V8 and by means of the latter is cut-ofi' from or placed into communication with a common suction chamber R; each suction valve being forced onto its seat by a spring F8 and is lifted oil its seat during the suction period of the pump. A suction pipe 9 is attached to the common suction chamber R. The suction valves of the twelve cylinders are arranged in the plane 0-03 of Fig. 1, in order that they may be operated in simple manner by a common cam-disc N.

Each suction valve comprises the valve seat, a valve stem J secured thereto and guided in the sleeve H of a member D, and a short inwardly projecting pin M, which co-acts with the cam disc N.

The suction chamber of each cylinder is cut-oft or placed into communication with an annular compression chamber P by a delivery valve Vd, the latter being forced onto its seat by a spring Fat and being lifted off its seat during the compression period of its pump.

The crank-shaft W runs in two ball bear- I pointer m, which is' adapted to play on a scale p and indicate the individual steps of the output of the pump.

In order to fix the crank 7c in the individ ual positions, the scale p is provided with a number of holes corresponding to the number of positions which the cam disc takes up during working. A small pin y, which is screwed to the shaft d of a handle it and is under the action of a spring f, is adapted to co-operate with the said holes.

Fig. 4 shows the shape of a cam disc for a twelve cylinder pump comprising two radial groups of six cylinderseach. The piston rods of the group arranged in the plane M (Fig. l) are drawn in full lines and the corresponding cylinders are designated with I?) to VIv, whilst the piston rods of the group located in the plane r-r (Fig. 1) are indicated in dotted lines and the corresponding cylinders are designated by the reference characters Ir to VIr. In order to readily observe the actual phases of the pumps, the two dead centre positions of the point of attachment of the piston rods to the pistons are indicated by two circles i and j. The highest output of the pump with twelve cylinders working is accomplished, if the cam disc is in the illustrated position. A reduction in the output of the pump takes place if the cam disc is rotated in the direction of the arrows indicated in Figs. 3 and 4 respectively. According to the present invention the stepwise reduction in the output of the pump is accomplished by placing out of action groups of cylinders in the following manner.

On rotating the cam disc clockwise for 5 degrees the pin M of the suction valve of the cylinder Iv passing through the period of compression is lifted and will now rest on the cam at the division mark 10. The cylinder Iv is now placed out of action and takes no part in the output of the pump, as during the suction period it will again force the drawn up fluid into the suction pi ing.

y the same rotation of the disc N and simultaneously with the placing out of action of the cylinder Po, the cylinder 1V1 of the second group whose individual phases of working correspond approximately with the working phases of the cylinder It (the movement of the phase of the said cylinder measured on the crank circle being 30 degrees) is placed out of action by means of lifting its suction valve pin M, so that only ten cylinders will work now. The suction valve pins of the other cylinders have not been influenced during this first mode of placing out of action, as the parts of the disc N involved thereby are provided with suitable curves of rest.

If it is desired to still further reduce the output of the pump, the disc N is rotated in the direction of the arrow for another 5 degrees. As will be seen the disposition and shape of the cams is such, that now the counter cylinders of the two cylinders already out of action are excluded from the output. These are in'the front group the cylinder IV?) (the cylinder opposite to I42) and in the rear grou the cylinder Ir (the cylinder opposite to I 2-).

Now the next cylinder to be placed out of action in the front group will be the cylinder I11) and simultaneously in the second group the cylinder Vr, whose individual working phases correspond approximately with the working phases of the first named cylinder. Also this placing out of action is accomplished by a rotation of the cam disc for a further 5 degrees. Now the next step comprises the placing out of action of the counter c linders of II?) and Vr, e. g. the cylinder '0 and H7. During the last step, the cylinders III?) and VIr are placed out of action whose individual, working phases correspond approximately with one another.

Now only two cylinders will be working, viz in the first group the cylinder VI?) and in the second group the cylinder IIIr.

In the illustrated construction a further step for accomplishing the no-load working of the aggregate has been dispensed with, as for this object .it is quite suflicient to short-circuit the suction and pressure piping of the aggregate. However if desired a no-load disconnecting step may be provided by suitably shaping the cam disc.

Further it will be remarked, that the cyl inders according to the illustrated construction are so arranged, that the adjustment of the phases of every simultaneously disconnected pair of cylinders is always 30 degrees measured on the crank circle. This is of importance as thereby these two cylinders wil thereby simultaneously accomplish the greatest part of their compression period, this being of importance if the cam disc is to be actuated by hand, as the lifting of a suction valve pin durin the pressure period of its corresponding cy 'nder requires great force particularly during a large-head.

The scope of the present invention is not limited to a twelve cylinder pump with two cylinder-groups, as also a pump with a larger number of cylinders, which are arranged in three or' more radial groups, may be employed. Also the suction valves of the same may be arranged in two or more radial groups. In that case two or more cam discs will have to be provided, the said discs being coupled with each other in order to efiect a perfect regulation.

If in the twelve cylinder pum according to the illustrated construction t e two cylinder groups are not displaced with respect to one another, the phases of the simultaneously disconnected cylinders are in complete accordance with each other, but a constructional drawback will arise in that the suction channels of the rear cylinder group will have to be suitably bent in order to lead them between the cylinders of the front group.

What, I claim is r 1. In multi-cylinder pumps, compressors and the like, the combination of a series of radially-arranged cylinders; each havin a suction valve combined therewith,-mova le cam means adapted to control the movement of the suction valves during the operation of the device, the said cylinders each having a piston associated therewith, and means adapted to control the movement of the pistons in said cylinders. a

2. A structure. according to claim 1 in which the said cam means consist of a revoluble cam disc having a series of curves of rest and steps formed on the periphery 7 thereof. 7

3. A structure according to claim 1 in which the stepwise movement of said cam means is adapted to control an increasing number of said suction valves so as to render their associated pump parts inoperative.

4:. A structure according to claim 1 in which the cylinders are arranged in sets in a plurality of planes, the said cylinders having suction channels, the suction channels of the cylinders located in one plane passing between the suction channels of the cylinders in the other plane.

5. A structure according to claim 1 in which the said movable cam means are adapted to simultaneously control the movement of the suction valves of two of said cylinders.

6. A structure according to claim 1 in which the said movable means are adapted to simultaneously control the movement of the suction valves of two non-aligned cylinders.

In testimony whereof I afiix my signature in presence of two witnesses.

GIULIO SILVESTRI. 

